1. Field of the Invention
The invention relates to an incandescent bulb for a motor vehicle. The invention relates especially to an incandescent bulb for a motor vehicle with performance which can withstand vibration during driving with the motor vehicle to a sufficient degree.
2. Description of Related Art
A motor vehicle is provided with an incandescent bulb for illumination while driving. The incandescent bulb must of course withstand vibration during driving with the motor vehicle to a sufficient degree. As the international standard, IEC810 requires that vibration up to roughly 1000 Hz be tolerated. Conventionally, certain methods have been used and arrangements devised as measures against this vibration, such as the arrangement of a support or the like. However, in these processes, there was the disadvantage that production is difficult because several working sequences are required for production.
The primary object of the present invention is to devise an incandescent bulb for a motor vehicle with a new arrangement which can withstand vibration during driving of a motor vehicle to a sufficient degree.
The object is achieved as in accordance with the invention in an incandescent bulb for a motor vehicle which comprises the following:
an envelope with a unilateral sealed portion;
two feed lines which extend into this envelope; and
at least one filament coil which forms an emission part, one end of which is connected to one of the feed lines and the other end of which is connected to the other feed line, and the main component of which is tungsten, wherein the filament coil has a spring constant of at least 25 g/mm and a weight at most equal to 100 mg.
The object is furthermore achieved as according to the invention by the main component of the above described inner lead being made of molybdenum having a diameter of at least 0.48 mm.
The object is moreover achieved by the envelope being made of glass, with quartz as the main component.